1. Field of the Invention
The present invention relates to a method and equipment for detecting sealing deficiencies, such as defective water traps and other sealing failures, within the drainage and vent systems for buildings.
2. Description of the Related Art
The purpose of a drainage system installed in a building is for conducting wastewater from sanitary appliances such as toilets, wash basins, bathtubs, etc into the sewer usually located in the underground of the building. In case of a multi-storey building, the drainage system has at least one vertical stack extending through the floor of each store and branch pipes for conducting the wastewater from each of the sanitary appliances present on each floor into the vertical stack by means of connectors. The stack and/or branch pipes or even each individual sanitary appliance may have been provided with air admittance valves or other appropriate venting arrangements and/or positive air pressure attenuator devices.
Water traps or water seals are generally used in relation with most sanitary equipment. Their purpose is to avoid fouled air coming from the sewer to be released into the environmental space or habitable space. The water trap is usually consisting of a U-shaped or bottle-shaped housings, generally connected to each of the sanitary appliances, and in which a certain amount of water remains in place sealing off the air from the stack and the sewer. Water closets have a water trap built into the fixture itself.
Under certain conditions, such as negative or positive air pressure conditions, the water traps could become disrupted which means that no sufficient amount of water remains in place to assure the sealing off from the discharge pipes and allowing fouled air from the sewer to enter into the habitable space. Such failures may result in pathogen transmission paths or system failure due to overpressure resulting in fouling the living space.
Venting of the drainage system is therefore important in order to prevent air pressure differentials in the system and in most of the systems use is of air admittance valves (AAV).
An air admittance valve (AAV) allows air to enter the drainage system through a one-way air valve when a sanitary fixture is operated and water flows through the pipes. When a column of waste water falls through the vertical stack, it entrains an airflow whose presence of necessity generates local suction or negative pressures. These are transmitted through the network and may lead to siphonnage of appliance water trap seals. In order to compensate for these negative pressures the membrane of the AAV is lifted temporarily and allows ambient air to enter the drainage system. The extent of these pressure fluctuations is determined by the fluid volume of the waste discharge. Excessive negative air pressure can siphon water from the water seals in the traps of sanitary appliances if no AAV are present.
On the other hand, if the air pressure within the drain becomes suddenly higher than ambient, this positive transient could cause wastewater (and air) to be pushed into the appliance, breaking the trap seal, with dire hygiene and health consequences. Positive air pressure attenuator devices have therefore been developed and proposed to reduce such risks of contamination, especially in high or multi-storey buildings.